Radio communication system and method for operating

ABSTRACT

A link established between a first network element that supports connection-oriented links, and a second network element that supports packet-oriented links, by establishing a connection-oriented link between the first network element and a gateway unit, and a packet-oriented link between the second network element and the gateway unit. A first link protocol that is associated with the first network element, and a second link protocol that is associated with the second network element are used. The first link protocol and the second link protocol differ by an information element that contains an address for the packet-oriented link between the second network element and the gateway unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to GermanApplication No. 10131092.7 and European Application No. 01115520.7 bothfiled on Jun. 27, 2001, the contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

Radio communication systems are used for transmitting information,speech or data, with the aid of electromagnetic waves over a radiointerface, also called an air interface, between a sending and areceiving radio terminal. Radio communication systems can be subdividedinto a core network in which payload and signaling data of a pluralityof terminals is transported over long distances on wires and via which aconnection can be implemented to a fixed communication network, and intoa Radio Access Network (RAN) via which the data received from theterminals is converted into a format suitable for the transmission inthe core network and vice versa, the form of data received by the corenetwork is adapted to radio transmission and forwarded to the relevantradio terminal, within the send area in which the terminal involved islocated.

Radio communication systems of the first and second generation arecurrently in use around the world and, because of the great demand formobile communication, are coming up against the limits of theircapacity. The emerging capacity problems are to be resolved by thethird-generation radio communication systems. One of thethird-generation radio communication systems which shows the greatestpromise of success is the Universal Mobile Telecommunication System(UMTS) that was specified by the standardization body 3GPP (ThirdGeneration Partnership Project) (see for example: B. Walke,Mobilfunknetze und ihre Protokolle (Mobile radio networks and theirprotocols), Volume 1, P. 385-387, Teubner Verlag 2000).

Data is transmitted circuit switched in the UTRAN access networkspecified for UMTS in accordance with the ATM procedure. In this casethe data which is to be transmitted over a connection is subdivided intoATM cells. The timing of ATM cells for a number of connections isinterleaved and the cells are transmitted over the same physicalconnection. The connection channel in this case remains the same for theduration of the transmission. An overview of the ATM method is forexample to be found in: B. Walke, Mobilfunknetze und ihre Protokolle(Mobile radio networks and their protocols), Volume 2, Chapter 8, Page255 to 290, Teubner-Verlag 1998.

The demands on mobile communications are being paralleled by theincreased demand for high bandwidth worldwide data communications. Thisdata is communicated over the Internet according to the IP (Internetprotocol) procedure. In this case data packets are transported overpacket-oriented connections, i.e. connectionless, between the users.With packet-oriented transmission there is a free choice of connectionchannel between the users only for the transmission of the relevant datapacket. A subsequent data packet can be routed via another channel. Itis thus possible that the order in which the data packets are receiveddiffers from the order in which they were sent.

There is an increasing demand to be able to also transmit large volumesof data by mobile communication with a high bandwidth. An IP-based radiocommunication network has therefore been proposed (see for example:3GPP, IP Transport in UTRAN Work Task Technical Report, in 3GPP TR25.933 2001), in which connections are made using the IP procedure.

SUMMARY OF THE INVENTION

The problem underlying the invention is that of specifying a radiocommunication system as well as a method of operating the same, which ison the one hand compatible with radio communication systems that supportcircuit-oriented connections, and on the other hand supports mobile datacommunications using connectionless communication.

The radio communication system has a first network element that supportscircuit-oriented connections and a second network element that supp Thefirst network element and the second network element are connected toeach other by an interworking unit. For transmission of data between thefirst network element and the second network element a circuit-orientedconnection is established between the first network element and theinterworking unit and a packet-oriented connection between the secondnetwork element and the interworking unit. In this case a firstconnection protocol that is used between the first network element andthe interworking unit and a second connection protocol that is usedbetween the second network element and the interworking unit isemployed. The first connection protocol and the second connectionprotocol are distinguished from one another by an information element toactivate the interworking unit which contains an address for thepacket-oriented connection between the second network element and theinterworking unit. In this way the different requirements imposed by thecircuit-oriented connection on one side and the packet-orientedconnection on the other side are reconciled. The interworking unitrepresents an intermediate node for data transmission, from which and towhich the individual subconnections are established.

The first network element can in this case be both a first accessnetwork and also a core network of the radio communication system thatsupports circuit-oriented connections. The second network element can beboth a second access network that supports packet-oriented connectionsand also, if the first network element is the first access network, acore network that supports packet-oriented connections.

In addition, in a radio communication system with only one accessnetwork and a core network, the first network element can be the accessnetwork that supports packet-oriented connections and the second networkelement the core network that supports circuit-oriented connections.Alternatively the access network can support circuit-orientedconnections and the core network packet-oriented connections.

Preferably the first connection protocol includes information elementsfor setting up the circuit-oriented connection between the first networkelement and the interworking unit. The second connection protocolincludes the information elements of the first connection protocol andthe information element for activating the interworking unit. Theinformation element for activating the interworking unit contains anaddress of the second network element, to which the packet-orientedconnection with the interworking unit is established. In addition thesecond connection protocol can contain further information elements.

The connection can be advantageously realized in this case in that thefirst network element supports ATM connections and the second networkelement supports IP connections. In this case signaling is exchanged forexample in the Radio Network Layer defined in the UMTS Model when aconnection is set up which contains the information that will be neededfor setting up the ATM connection between the first network element andthe interworking unit. This information includes for example: TheTransport Layer Address (TLA) and Transport Association (TA). In theTransport Network Layer: the first connection protocol and the secondconnection protocol are then exchanged.

The connection between the first network element and the interworkingunit will preferably be established as an AAL2 connection. Theinformation element for activating the interworking unit that iscontained in the second connection protocol includes an IP endpointidentification of the second network element.

Preferably the first connection protocol, with the aid of which theconnection between the first network element and the interworking unitis set up, features the information elements according to an ALCAPprotocol. The second connection protocol additionally contains anaddress and a UDP port, to which the packet-oriented connection will beestablished.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome more apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a block diagram of a radio communication system in accordancewith the invention.

FIG. 2 is a transmission sequence diagram of connection setup, datatransmission and connection cleardown between an IP-based and anATM-based access network.

FIG. 3 is a table of protocols used for establishing the connectionbetween the IP-based and ATM-based access network.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

A radio communication system (see FIG. 1) has a first access network Z1,a second access network Z2 and a core network S. The first accessnetwork Z1 has base station nodes B1 which are connected via an lubinterface with a radio network controller RNC1. The first access networkZ1 supports ATM-based connections.

The second access network Z2 has a number of base stations NodeB2. Thebase stations NodeB2 are connected to a radio network controller RNC2.The radio network controller RNC2 has one or more user plane servers UPSand one or more radio control servers RCS that are connected to eachother via node K. The radio control server RCS takes over the controland monitoring of the air interface, as well as of the radio resources,while the user plane server UPS takes over transmission of the payloaddata. This type of division of the payload data and the signaling datawas for example: proposed in German Patent Application P 100 46342.8-31. The second access network Z2 supports IP-based connections.

The radio network controller RNC1 is connected via an interface lur witha first interworking unit IWU1. The first interworking unit IWU1 isconnected on the other side with the second access network Z2. Theconnection is for example realized via node K of the radio networkcontroller RNC2.

In addition, Radio Network Controller RNC1 is connected via an interfacelucs with the Mobile Switching Center MSC of the core network and via aninterface lups for packet-switching data with a packet data node SGSN ofthe core network S. The core network S supports ATM-based connections.

The radio network controller RNC2 is connected via a second interworkingunit IWU2 of the second access network Z2 with the core network S.

To set up a data connection between the first access network Z1 and thesecond access network Z2 or between the second access network Z2 and thecore network S an ATM-based connection between the second access networkZ2 and the interworking unit IWU1 or IWU2 is set up in each case and afurther ATM-based connection between the interworking unit IWU1 and thefirst access network Z1 or the interworking unit IWU2 and the corenetwork S.

To set up a connection between the first access network Z1 and thesecond access network Z2 an RL Setup Request will be sent transparentlyfor the interworking unit IWU1 from the radio network controller RNC1 ofthe first access network Z1 to the radio network controller RNC2 of thesecond access network Z2 (see FIG. 2). There follows an RL SetupResponse). With this response the connection parameters TLA and TA willbe transmitted.

Subsequently the connection will be set up via the transport networkcontroller. To do this the radio network controller RNC2 of the secondaccess network Z2 will send an Establishment Request ERQ) to theinterworking unit IWU1. This signaling message contains the argumentsNSEA for destination NSAP Service endpoint address, DSAID forDestination signaling association identifier, ALC for Linkcharacteristics, OSAID for Originating signaling association identifier,SUGR for Served user generated reference, SSISU for Service specificInformation (SAR-unassured) as well as IPEID that contains an address ofthe radio network controller RNC2 to which a connection from theinterworking unit IWU1 to the radio network controller RNC2 is to be setup. In this case NSAP stands for Network Service Access Point and SARfor Segmentation and Reassembly (Sublayer).

Between the interworking unit IWU1 and the first access network Z1 asignaling message Establishment Request ERQ) will be sent. In this casethe parameter CEID stands for Connection Element Identifier. Theremaining parameters are taken from the signaling message between thesecond access network Z2 and the interworking unit IWU1.

The first access network Z1 responds to the interworking unit with anEstablishment Confirm ECF. The interworking unit responds to the secondaccess network Z2 with an Establishment Confirm). In this signalingmessage the second access network Z2 is notified about an address of theinterworking unit IWU1 to which the connection is to be set up.

Thus the connection from the second access network Z2 to theinterworking unit IWU1 and from the interworking unit IWU1 to the firstaccess network Z1 and vice versa is established. Payload data, shown bythe black arrows, is transmitted. The payload data will be transmittedbetween the second access network Z2 and the interworking unit IWU1 overa IP/UDP connection. Between the interworking unit IWU1 and the firstaccess network Z1 the payload data will be transmitted over an ATM-basedAAL2 connection.

After the end of data transmission the connection will be cleared downagain. To do this an RL Release Request for the interworking unit willbe exchanged transparently between the access network Z2 and the firstaccess network Z1. The clear down of the connection between the secondaccess network and interworking unit IWU1, as well as between theinterworking unit IWU1 and the first access network Z1 follows.

In FIG. 3 the protocols used for this are shown. In the uppermost layera first connection protocol V1 is used for the first access network anda second connection protocol V2 is used for the second access network.The first connection protocol V1 is the protocol standardized under thedesignation Q.2630.1 or ALCAP for setting up ATM-based connections. Thesecond connection protocol V2 contains the information elements listedin the first connection protocol V1 and in addition contains an IPendpoint identification which allows the connection between the secondaccess network Z2 and interworking unit IWU to be set up.

The clear down of a connection between the second access network Z2 andthe core network S via the second interworking unit IWU2 uses the sameprocedures.

The invention has been described in detail with particular reference topreferred embodiments thereof and examples, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention.

1. A radio communication system, comprising: an interworking unit; afirst network element supporting circuit-oriented connections and usinga first connection protocol to set up a circuit-oriented connection withsaid interworking unit; and a second network element supportingpacket-oriented connections and using a second connection protocol toset up a packet-oriented connection with said interworking unit forinterconnection with said first network element via said interworkingunit, the second connection protocol being distinguished from the firstconnection protocol by an activating information element in the secondnetwork protocol for activating the interworking unit which contains anaddress for the packet-oriented connection between said second networkelement and said interworking unit.
 2. The radio communication systemaccording to claim 1, further comprising a core network; a first accessnetwork; and a second access network, wherein said first network elementis part of said first access network, and wherein said second networkelement is part of one of said second access network and said corenetwork.
 3. The radio communication system according to claim 1, furthercomprising a core network; a first access network; and a second accessnetwork, wherein said first network element is part of said corenetwork, and wherein said second network element is part of said secondaccess network.
 4. The radio communication system according to claim 1,wherein the first connection protocol includes circuit-orientedinformation elements for setting up the circuit-oriented connectionbetween said first network element and said interworking unit, whereinthe second connection protocol contains the circuit-oriented informationelements of the first connection protocol and the activating informationelement, and wherein the activating information element contains anaddress of said second network element to which the packet-orientedconnection with said interworking unit is set up.
 5. The radiocommunication system according to of the claim 4, wherein said firstnetwork element supports ATM-connections, and wherein said secondnetwork element supports IP connections.
 6. The communication systemaccording to claim 5, wherein the circuit-oriented connection betweensaid first network element and said interworking unit is set up as anAAL2 connection, and wherein the activating information element containsan IP endpoint identification of said second network element.
 7. Theradio communication system according to claim 6, wherein the firstconnection protocol includes an ALCAP information element in accordancewith an ALCAP protocol, and wherein the second connection protocolcontains also includes a UDP port, to which the packet-orientedconnection can be set up.
 8. A method for operating a radiocommunication system, comprising: establishing a circuit-orientedconnection between a first network element and an interworking unitusing a first connection protocol assigned to the first network element;establishing a packet-oriented connection between a second networkelement and the interworking unit using a second connection protocolassigned to the second network element; and distinguishing between thefirst and second connection protocols by an activating informationelement in the second connection protocol that contains an address foractivation of the interworking unit for the packet-oriented connectionbetween the second network element and the interworking unit.
 9. Themethod according to claim 8, wherein the radio communication systemincludes a core network, a first access network, and a second accessnetwork, wherein the first network element is part of the first accessnetwork, and wherein the second network element is part of one of thesecond access network and the core network.
 10. The method according toclaim 8, wherein the radio communication system includes a core network,a first access network, and a second access network, wherein the firstnetwork element is part of the core network, and wherein the secondnetwork element is part of the second access network.
 11. The methodaccording to claim 8, wherein the first connection protocol includescircuit-oriented information elements for setting up thecircuit-oriented connection between the first network element and theinterworking unit, wherein the second connection protocol contains thecircuit-oriented information elements of the first connection protocoland the activating information element, and wherein the activatinginformation element contains an address of the second network element towhich the packet-oriented connection with the interworking unit is setup.
 12. The method according to claim 11, wherein the first networkelement supports ATM-connections, and wherein the second network elementsupports IP connections.
 13. The method according to claim 12, whereinthe connection between the first network element and interworking unitis set up as an AAL2 connection, and wherein the activating informationelement contains an IP endpoint identification of the second networkelement.
 14. The method according to claim 13, wherein the firstconnection protocol includes an ALCAP information element in accordancewith an ALCAP protocol, and wherein the second connection protocolcontains also includes a UDP port, to which the packet-orientedconnection can be set up.